The present invention relates to fuser release agents or fusing oils useful in fusing subsystems in electrostatographic, including digital and color, apparatuses. In embodiments, the release agents comprise a fluorosurfactant, which is useful in compatibilizing the dissimilar materials in a release agent, and for reducing surface tension between the liquid release agent and the solid surface of the fuser member. In embodiments, the fluorosurfactant comprises pendant acid or ester groups. In other embodiments, the fluorosurfactant contains pendant olefin groups. In still yet another embodiment, the fluorosurfactants contain pendant silane groups. In other embodiments, the fluorosurfactants contain pendant alcohol groups. In embodiments, the release agent comprises a silicone oil, and in specific embodiments, a polydimethylsiloxane oil. In embodiments, the silicone release agent may or may not contain functional groups.
In a typical electrostatographic reproducing apparatus, a light image of an original to be copied is recorded in the form of an electrostatic latent image upon a photosensitive member and the latent image is subsequently rendered visible by the application of electroscopic thermoplastic resin particles which are commonly referred to as toner. The visible toner image is then in a loose powdered form and can be easily disturbed or destroyed. The toner image is usually fixed or fused upon a support which may be the photosensitive member itself or other support sheet such as plain paper.
The use of thermal energy for fixing toner images onto a support member is well known. To fuse electroscopic toner material onto a support surface permanently by heat, it is usually necessary to elevate the temperature of the toner material to a point at which the constituents of the toner material coalesce and become tacky. This heating causes the toner to flow to some extent into the fibers or pores of the support member. Thereafter, as the toner material cools, solidification of the toner material causes it to be firmly bonded to the support.
Several approaches to thermal fusing of electroscopic toner images have been described. These methods include providing the application of heat and pressure substantially concurrently by various means, a roll pair maintained in pressure contact, a belt member in pressure contact with a roll, a belt member in pressure contact with a heater, and the like. Heat may be applied by heating one or both of the rolls, plate members, or belt members.
It is important in the fusing process that minimal or no offset of the toner particles from the support to the fuser member take place during normal operations. Toner particles offset onto the fuser member may subsequently transfer to other parts of the machine or onto the support in subsequent copying cycles, thus increasing the background or interfering with the material being copied there. The hot offset temperature or degradation of the hot offset temperature is a measure of the release property of the fuser, and accordingly it is desired to provide a fusing surface, which has a low surface energy to provide the necessary release.
To ensure and maintain good release properties of the fuser, it has become customary to apply release agents to the fuser roll during the fusing operation. Typically, these materials are applied as thin films of, for example, silicone oils such as polydialkyl siloxane, and more specifically, polydimethyl siloxane (PDMS). The fuser oils may contain functional groups or may be non-functional, or may be blends of functional and nonfunctional. Functional groups may include amino, mercapto, hydride, or other functional groups.
It is desired to have a release agent that is chemically compatible with the outer layer of the fuser member. In embodiments wherein fillers are used in the outer layer of a fuser member, it is desired to use a release agent having functional groups to react with the outer layer or fillers in the outer layer of the fuser member. The reaction between the functional groups of the release agent and the outer layer of the fuser member binds the release agent to the outer layer, thereby enabling full coverage of the fuser member surface and providing an effective barrier layer that allows for toner and paper release. In this way, a longer fuser release life is achieved.
However, problems result with certain outer layers of the fuser member are used, or when certain types of toner, ink or other print formulations are used in an electrostatographic apparatus. In addition, with known release agents, problems result in that POST-IT(copyright) notes, adhesives, laminates and the like, do not adhere sufficiently to the paper once the release agent has come into contact with the paper. This is especially true for amino-functional polydimethyl siloxane release agents, in which the release agent bonds to the cellulose of paper, and remains coated to the paper following fusing.
The use of a fluorosurfactant can help control these problems by increasing the compatibility between dissimilar components in the outer layer and the toner, ink or other print formulations. In this manner, less expensive outer layer materials may be coated on the fuser member. Similarly, off the shelf release agents may be used and specific release agents may not have to be formulated for specific outer fuser member layers. These both result in a significant cost savings. Moreover, fluorosurfactants aid in preventing release agents to remain on the surface of the print media (for example, paper), thereby improving copy or print quality. Therefore, in embodiments, the pendant release agents reduce or eliminate oil-on-copy surface, and thus contribute to improved copy quality. In addition, the use of fluorosurfactants improves wettability, thereby increasing copy or print quality.
U.S. Pat. No. 5,735,945 discloses use of a polydialkoxysilane oil and nonionic surfactants such as fluorosurfactants as a release agent for fuser members.
Embodiments of the present invention include: a release agent comprising a polydimethylsiloxane and a fluorosurfactant, wherein the fluorosurfactant is other than a silicone glycol polymer, a perfluoroalkylsubstituted polyethylene glycol, or a perfluoroalkylsubstituted silane.
Embodiments also include: a release agent comprising a polydimethylsiloxane and a fluorosurfactant having pendant groups selected from the group consisting of acid groups, ester groups, olefin groups, alcohol groups, silane groups, and mixtures thereof, wherein the fluorosurfactant is other than a silicone glycol polymer, a perfluoroalkylsubstituted polyethylene glycol, or a perfluoroalkylsubstituted silane.
Embodiments further include: a composition comprising a polydialkylsiloxane and a fluorosurfactant, wherein said fluorosurfactant is other than a silicone glycol polymer, a perfluoroalkylsubstituted polyethylene glycol, or a perfluoroalkylsubstituted silane.
In addition, embodiments include: an image forming apparatus for forming images on a recording medium comprising: a charge-retentive surface to receive an electrostatic latent image thereon; a development component to apply toner to the charge-retentive surface to develop the electrostatic latent image to form a developed image on the charge retentive surface; a transfer component to transfer the developed image from the charge retentive surface to a copy substrate; a fuser member for fusing toner images to a surface of the copy substrate; and a release agent comprising a polydimethylsiloxane and a fluorosurfactant other than a silicone glycol polymer, a perfluoroalkylsubstituted polyethylene glycol, or a perfluoroalkylsubstituted silane.